Trends in color xerographic printing include reduced box weight and size, higher process speeds and parallel printing in order to minimize cost, improve productivity and reliability. This has led to a drive for smaller photoreceptors, particularly drum photoreceptors which results in squeezing the space available to the subsystem components disposed around the photoreceptor. In electrophotographic systems, after the transfer of the toner to the paper, the toner is cleaned off the photoreceptor and the photoreceptor is exposed to an erase light to remove the residual latent image. However, long print runs of a single image can lead to variations in optical transparency related to image content. Further conductive ground planes based on strongly reducing metals such as Al, Ti, Zr are gradually converted to their oxides as a result of xerographic cycling. Also, holes traversing the photoreceptor in combination with ambient water electrochemically convert the metals to their insulating oxides resulting in a change in charge acceptance and transparency. Consequently both the erase illumination and ground plane conductivity vary spatially according to image content leading to image ghosts which limits photoreceptor life. Suitable materials for non-electrochemically reactive, optically transparent conductive ground planes are limited. Dispersed carbon particles are not electrochemically reactive but they are unsuitable material for conductive ground plane because of poor optical transparency. Other alternative optically transparent conductive ground planes such as cuprous oxide and conducting polymers including polypyrrole and polyaniline have problems due to relative immaturity of the technology.
Furthermore, it is difficult to achieve both high optical transparency and low ground plane resistivity (i.e. sheet resistivity) at the same time in either carbon filled or conductive ground planes based on metals such as Al, Ti, Zr. Moreover, belt photoreceptors that erase by illuminating through the ground plane, i.e. by “rear erase” require further increase in erase lamp intensity. In addition, the use of an anti-curl back coat on a belt photoreceptor further increases the need for higher intensity erase illumination because over time its surface becomes rather scratched and abraded. Consequently some of the illumination is scattered or diffracted and is prevented from reaching the charge generator layer.
Thus, there is a need to overcome these and other problems of the prior art to provide a method and system for internal erase illumination or “self erasing” of the photoreceptor comprising electroluminescent conductive ground plane.